com.neeve.aep

Interface IAepEnvironmentProvider

public interface IAepEnvironmentProvider

Represents an environment data provider

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	IAepEnvironmentProvider.BufferManager Represents an interface to a environment provider's buffer manager The AEP engine manages the buffers to which the environment providers record information to be replicated.
static class	IAepEnvironmentProvider.TransactionAction Used to specify what action a provider should take during a transaction

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Invoked to close an environment provider.
void	onTransactionEnd() Invoked on the end of a transaction.
void	onTransactionStart(ByteBuffer buffer, IAepEnvironmentProvider.TransactionAction action) Invoked at the start of a transaction.
void	setBufferManager(IAepEnvironmentProvider.BufferManager bufferManager) Supplies the environment provider with a buffer manager.

Method Detail

setBufferManager

void setBufferManager(IAepEnvironmentProvider.BufferManager bufferManager)

Supplies the environment provider with a buffer manager.

Parameters:

bufferManager - The buffer manager.

An AEP engine invokes this method on registration of the environment provider to supply the provider with a buffer manager for use by the provider to allocate buffers to store the environment change log.

onTransactionStart

void onTransactionStart(ByteBuffer buffer,
                      IAepEnvironmentProvider.TransactionAction action)

Invoked at the start of a transaction.

Parameters:

buffer - The environment buffer. The provider should use this buffer to record information to be replicated or replay replicated as dictated by the action parameter. The buffer markers will already be prepared by the engine prior to invoking this method. The provider should begin recording at the position marker and increment the position marker to always point to the end of the recorded data. After returning from the onTransactionEnd() at the end of the recording, the engine computes the length of the recorded data using the difference between the position marker as set at the end of the transaction with what is what at the beginning.

action - Indicates whether the provider should use the buffer to record or play back replicated information.

An AEP engine invokes this method at the start of a transaction. The provider should use the supplied buffer during the course of the transaction. The action parameter specifies whether the provider should record or playback to/from the buffer. If asked to record, then the provider should record data to be replicated in the buffer starting at the buffer position marker and incrementing the position marker to always point to the end of the recorded data. The provider should use the buffer manager to resize the buffer in the event of an overflow. If requested to playback (i.e. on the backup), the provider should play back the data in the buffer to reconstitute primary state on the backup.

onTransactionEnd

void onTransactionEnd()

Invoked on the end of a transaction.

An AEP engine invokes this method at the end of a transaction to notify the provider of the completion of a transaction. The method is invoked purely for notification purposes e.g. for a provider on a backup to validate that all the recorded information was indeed played back (for, if not, it indicates a serious error)

close

void close()

Invoked to close an environment provider.

An AEP engine invokes this method when it is stopped to enable the environment provider to perform any cleanup.